Using his backyard telescope, Australian amateur astronomer Anthony Wesley discovered that the planet Jupiter was recently struck by something very large — leaving an Earth-sized impact site: New NASA Images Indicate Object Hits Jupiter.

Scientists have found evidence that another object has bombarded Jupiter, exactly 15 years after the first impacts by the comet Shoemaker-Levy 9.

Following up on a tip by an amateur astronomer, Anthony Wesley of Australia, that a new dark “scar” had suddenly appeared on Jupiter, this morning between 3 and 9 a.m. PDT (6 a.m. and noon EDT) scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., using NASA’s Infrared Telescope Facility at the summit of Mauna Kea, Hawaii, gathered evidence indicating an impact.

New infrared images show the likely impact point was near the south polar region, with a visibly dark “scar” and bright upwelling particles in the upper atmosphere detected in near-infrared wavelengths, and a warming of the upper troposphere with possible extra emission from ammonia gas detected at mid-infrared wavelengths.

“We were extremely lucky to be seeing Jupiter at exactly the right time, the right hour, the right side of Jupiter to witness the event. We couldn’t have planned it better,” said Glenn Orton, a scientist at JPL.

More details:
Amateur Finds New Earth-Sized Blot on Jupiter